Mass transfer system for stabilizing an airship and other vehicles subject to pitch and roll moments

ABSTRACT

The invention relates to a mechanism to control the pitch and/or roll and/or center of gravity of a vehicle. The first embodiment is a track-based mass transfer system in which pathways are positioned along or radially terminate at a central horizontal plane of the vehicle to move one or more mass transfer devices to a desired location to control the pitch and/or roll and/or center of gravity of the vehicle. A second embodiment is a fluid mass distribution system in which one or more conduits selectively distribute a fluid to one or more tanks positioned near a central horizontal plane of the vehicle to control the pitch and/or roll and/or center of gravity of the vehicle.

FIELD OF THE DISCLOSURE

Various embodiments of the invention relate generally to a system forstabilizing a vehicle subject to pitch and roll moments. Moreparticularly, at least one embodiment of the invention relates to a masstransfer system for stabilizing an airship subject to pitch and rollmoments.

DESCRIPTION OF RELATED ART

Typically, a lighter-than-air or buoyant aircraft (commonly referred toas an “airship”) includes an envelope, one or more gas-filled cellscontaining a lifting gas, a propulsion system, a steering system and agondola or carriage compartment. Airships, like other aircraft,generally rely on external control mechanisms (e.g., elevators, fins,rudders, etc.) to control the attitude of the airship and stabilize theairship in flight. Airships are generally subject to moments along threeaxes, which can be defined by three primary control vectors. The threeprimary control vectors are pitch (rotation about the lateral axis),roll (rotation about the longitudinal axis) and yaw (rotation about thevertical axis).

Conventional control systems rely on external control mechanisms tocreate aerodynamic forces causing the airship to pitch, roll and/or yawas desired, primarily to counteract external forces (e.g., a gust ofwind or clouds) that would otherwise destabilize the airship in flight.Conventional control systems are also used to adjust the angle of attackfor airships that depend on dynamic lift and reverse dynamic lift fortakeoff and landing. These external control mechanisms, however, areinefficient because they add significant weight to the airship and theiroperation also generates drag, which slows the airship as it moves inthe desired direction. These external control mechanisms generate drageven when they are not activated, because they tend to disrupt theaerodynamic shape of the airship. Additionally, these conventionalcontrol systems do not perform well in very slow or hovering flightbecause insufficient airflow is generated over the external controlmechanisms.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a rear perspective view of an airship that employs acontrol system for stabilizing the pitch and/or roll of the airshipaccording to one embodiment of the invention.

FIG. 2 illustrates an underside view of the airship of FIG. 1 having acontrol system that employs a mass transfer system to stabilize and/ororient the airship according to one embodiment of the invention.

FIG. 3 illustrates a partial perspective side view of the airship ofFIG. 1 having a control system according to one embodiment of theinvention.

FIG. 4 illustrates a top view of a track-based mass transfer system forcontrolling the pitch and/or roll of an airship according to oneembodiment of the invention.

FIG. 5 illustrates a partial cross-sectional side view of thetrack-based mass transfer system illustrated in FIG. 4 according to oneembodiment of the invention.

FIG. 6 illustrates a partial perspective view of a mass transfer devicethat travels along a pathway of a track-based mass transfer systemaccording to one embodiment of the invention.

FIG. 7 illustrates an end view of the mass transfer device of FIG. 6positioned inside the pathway of a track-based mass transfer systemaccording to one embodiment of the invention.

FIG. 8 illustrates a perspective view of the mass transfer device ofFIG. 6 according to one embodiment of the invention.

FIG. 9 illustrates a side view of the mass transfer device of FIG. 6according to one embodiment of the invention.

FIG. 10 is a block diagram illustrating a control system for controllingthe mass transfer devices of FIG. 6 to adjust the pitch and/or roll ofthe airship according to one embodiment of the invention.

FIG. 11A illustrates a top view of a track-based mass transfer systemhaving six mass transfer devices used to adjust a vehicle's center ofgravity and provide pitch and roll stability according to one embodimentof the invention.

FIG. 11B illustrates a top view of a track-based mass transfer systemhaving six mass transfer devices used to adjust a vehicle's center ofgravity and provide pitch and roll stability according to one embodimentof the invention.

FIG. 12A illustrates a movable gondola attached to a track, which canalso be used to adjust a vehicle's center of gravity according to oneembodiment of the invention.

FIG. 12B illustrates one or more movable propulsion motors attached toone or more tracks, which can also be used to adjust a vehicle's centerof gravity according to one embodiment of the invention.

FIG. 13 illustrates a fluid mass transfer system for controlling thepitch and roll of the airship of FIG. 1 according to one embodiment ofthe invention.

FIG. 14 illustrates a block diagram of the fluid mass transfer system ofFIG. 13 according to one embodiment of the invention.

FIG. 15 illustrates a top view of a fluid mass transfer system forcontrolling the pitch and roll of the airship of FIG. 1 according to oneembodiment of the invention.

SUMMARY OF THE INVENTION

One embodiment of the invention is an airship that may include a hullhaving an inner surface defining a cavity and an outer surface, a cabincoupled to the outer surface of the hull, a propulsion device coupled tothe outer surface of the hull for providing yaw control, and a sensorfor detecting a pitch and/or roll movement of the hull. The airship mayalso include a pathway positioned adjacent to the hull, a mass transferdevice configured to move along the pathway, and a control device forreceiving a pitch signal and/or a roll signal from the sensor and, usingthe pitch signal and/or the roll signal, controlling the movement of themass transfer device along the pathway to stabilize the airship and/orto achieve a desired pitch and/or roll orientation. The mass transferdevice may be configured to move along the pathway to adjust theairship's center of gravity toward the airship's center of pressure.

One embodiment of the invention relates to a stability control systemfor a vehicle that employs a mechanism to control the pitch and/or rollof the vehicle. The system may include a pathway disposed adjacent to aperimeter of the vehicle, a mass transfer device movably coupled to thepathway, and a controller configured to cause the mass transfer deviceto move from a first location on the pathway to a second location on thepathway to achieve a desired pitch or roll orientation.

One embodiment of the invention provides a stability control system fora lenticular, disc-shaped airship which includes one or more tracksdisposed around the internal and/or external equator of the airship andone or more mass transfer devices (e.g., moveable units such asmechanical or robotic sleds) coupled to the one or more tracks, eachmass transfer device carrying or acting as a weight and including adrive mechanism to move the mass transfer device along the one or moretracks. One or more sensors may be used to detect the pitch and/or rollof the airship and provide one or more corresponding output signals. Acontroller may receive one or more output signals from the one or moresensors and provide one or more signals to move the one or more masstransfer devices to a location along the one or more tracks to achieve adesired pitch and/or roll orientation.

One embodiment of the invention relates to a system for providing pitchand roll stability to a vehicle. The system may include a plurality oftanks disposed about a central horizontal plane of the vehicle, aconduit coupled to the plurality of tanks for carrying a fluid to andfrom the plurality of tanks, and a controller configured to cause thefluid to move to or from the plurality of tanks to achieve a desiredpitch and/or roll orientation.

DETAILED DESCRIPTION

Methods and systems that implement the embodiments of the variousfeatures of the invention will now be described with reference to thedrawings. The drawings and the associated descriptions are provided toillustrate embodiments of the invention and not to limit the scope ofthe invention. Reference in the specification to “one embodiment” or “anembodiment” is intended to indicate that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least an embodiment of the invention. The appearancesof the phrase “in one embodiment” or “an embodiment” in various placesin the specification are not necessarily all referring to the sameembodiment. Throughout the drawings, reference numbers are re-used toindicate correspondence between referenced elements. In addition, thefirst digit of each reference number indicates the figure in which theelement first appears.

In the following description, certain terminology is used to describecertain features of one or more embodiments of the invention. Forinstance, the term “pathway” may include, but is not necessarily limitedto, a track, a guide, a passageway, a path, a rail, a tube, and/or atunnel on or through which a device (e.g., a mass transfer device) maybe guided and/or may ride. The term “mass transfer device” may include,but is not necessarily limited to, a sled, a weight, a cart, and/or adevice capable of moving adjacent to, along, through or on the pathway.The term “fluid” may include, but is not necessarily limited to, a gas,an aqueous solution, water, oil, air, and/or other substance.

FIG. 1 illustrates a rear perspective view of an airship 100 thatemploys a control system (e.g., a pitch and/or roll control system asshown in FIG. 10) for stabilizing the pitch and/or roll of the airship100 according to one embodiment of the invention. The airship 100 mayinclude a hull 102, a propulsion device 104, a gondola 106 and aplurality of landing supports and wheels 108. The invention describedherein is not limited to airships and thus may be used on other vehiclessubject to pitch and roll moments. For example, one embodiment of theinvention relates to a control system for a boat (e.g., ship, sailboat,yacht, catamaran, or other water-borne vessel) that employs a masstransfer system to stabilize and/or orient the boat.

The hull 102 may be made of a flexible (e.g., fabric) and/or rigid(e.g., lightweight metal or composite) material, or a combinationthereof, that provides structural integrity to the airship 100 eitheralone or in conjunction with an internal structural framework. The hull102 may be configured in the shape of a sphere, a flattened sphere(i.e., lenticular or “saucer” shape), a donut, a cigar (i.e., resemblinga traditional blimp), and various other aerodynamic shapes.

The airship 100 may be non-rigid (the airship's shape is dependent onthe gas inside its flexible fabric envelope having a higher pressurethan the outside atmosphere), semi-rigid (similar to a non-rigidairship, but with a rigid keel to help maintain its shape), rigid (theairship's shape is maintained by an internal structural frameworkcovered with fabric and the lifting gas is contained by a separate gascell or cells located within that structural framework) or monocoque(the airship's shape is maintained by a lightweight metal and/orcomposite load-bearing hull and the lifting gas is contained eitherdirectly within that hull or within a separate gas cell or cellscontained within that hull).

The hull 102 may be designed to contain lighter-than-air gases (e.g.,helium, hydrogen, air, or a mixture of any number of gases) directly orto enclose one or more balloons or cells that may containlighter-than-air gases. The lighter-than-air gases within the hull 102may provide all or most of the lifting force so that little or noadditional energy is expended to lift the airship 100 into the air. Inone embodiment of the invention, the hull 102 may be pressurized.

One embodiment of the invention provides a monocoque airship having alightweight metal and/or composite hull, which directly contains alifting gas and provides rigidity to the airship without the need for aseparate structural framework.

One embodiment of the invention provides a pressurized fabric envelopethat is reinforced with an internal lightweight metal and/or a compositering disposed around the equator of the hull 102. The composite ringprovides solid attachment points for the fabric envelope, and allows itto be pressurized to a greater degree without losing its lenticularshape and deforming into a spherical shape under pressure. Thelightweight metal and/or the composite ring disposed around the equatorof the hull 102 also serves as a pathway for the various embodiments ofthe track-based mass transfer system described herein. Regardless of thetype of construction that may be employed, the invention may beimplemented to provide stability control to any airship.

The airship 100 may also include one or more propulsion devices orsystems 104A and 104B, including, but not limited to, propellers,engines, motors, electro-kinetic drives and/or jets, which serve togenerate a thrust to move the airship 100 in a particular direction. Thepropulsion system 104A may operate in the same or in a different manneras the propulsion system 104B, and may be configured to provide yawcontrol.

The airship 100 may also include a gondola 106 to house an operator,passengers, cargo, equipment, a flight deck, etc. As shown in FIG. 1,the gondola 106 may be positioned outside the hull 102 and centeredabout the underside of the hull 102 (see also FIG. 2). In otherembodiments, the gondola 106 may be located either inside or outside thehull 102 at various locations, and may be located on a track or otherdevice allowing the gondola 106 to be moved forward or aft as desired toadjust the airship's center of gravity (see also FIG. 12A). The airship100 may include a plurality of landing supports and wheels 108 fortakeoff and landing.

FIG. 2 illustrates an underside view of the airship 100 of FIG. 1 havinga control system (e.g., a pitch and/or roll control system as shown inFIG. 10) that employs a mass transfer system to stabilize and/or orientthe airship 100. In one embodiment of the invention, the airship 100 hasa lenticular hull 102. This view of the airship 100 also shows thegondola 106 centered about the underside of the airship 100. The airship100 may also include two or more propulsion motors 104A and 104Bdisposed at the underside and at opposite locations, sides and/or endsof the airship 100.

FIG. 3 illustrates a partial perspective side view of the airship 100 ofFIG. 1 having a control system (e.g., a pitch and/or roll control systemas shown in FIG. 10) that employs a mass transfer system to stabilizeand/or orient the airship 100. In one embodiment, each propulsion motor104A and 104B may have two or more propellers.

The airship 100 illustrated in FIGS. 1-3 has an aerodynamic hull 102with no external control mechanisms for controlling the pitch and/orroll of the airship 100 (the propulsion motors 104A and 104B may serveas yaw control). This configuration minimizes weight and drag andincreases operational efficiency. Conventional external controlmechanisms (e.g., fins, elevators, rudder, etc.) for controlling thepitch and/or roll moments tend to increase drag and decrease efficiency,and are superseded and replaced by the features of the inventiondescribed herein.

FIG. 4 illustrates a top view of a track-based mass transfer system 400for controlling the pitch and/or roll of the airship 100 according toone embodiment of the invention. The mass transfer system 400 includesone or more pathways positioned along the interior or exterior equatorof the hull 102 of the airship 100 to move one or more mass transferdevices 410, 412, 414 and 416 to a desired location, thereby affectingthe pitch and/or roll of the airship 100 as desired. In one embodiment,four non-overlapping contiguous tracks 402, 404, 406 and 408 arepositioned along the interior equator of the hull 102. Each track 402,404, 406 and 408 may serve to guide and/or move one or moremass-transfer devices 410, 412, 414 and 416 to a desired location onthat track. In other embodiments of the invention, a single track may beused to move one or more mass-transfer devices 410, 412, 414 and 416 toa desired location along the interior and/or exterior equator of thehull 102. In yet another embodiment, a plurality of tracks that runalong the interior or exterior equator of the hull 102 may be employed.Similarly, a single track having two or more independent rails thereonmay be used to move one or more mass transfer devices 410, 412, 414, 416to a desired location on the track. In another embodiment, one or moretracks can be radially positioned from the center of the hull 102 to theperiphery of the hull 102.

In one embodiment, the mass-transfer devices 410, 412, 414 and 416 setin or on the tracks 402, 404, 406 and 408 may be moved via motors (e.g.,servo motors, stepper motors, etc.), pneumatics, hydraulics and/orlinear magnetic levitation devices to a desired position. In a stableposition, the mass transfer devices 410, 412, 414 and 416 may be equallydistributed or spaced along the circumference of the airship 100 and/orthe hull 102. For instance, the mass transfer devices 410, 412, 414 and416 may rest at or near the center of their respective tracks 402, 404,406 and 408 so that they may be moved in either direction to adjust thepitch and/or roll of the airship 100. To counteract an external force(e.g., a gust of wind or clouds) causing a particular pitch and/or rollmoment, one or more of the mass transfer devices 410, 412, 414 and 416may be moved along their respective track(s) to cause a desired amountof weight to be shifted to a particular position and, for example,thereby return the airship 100 to a level position. A controller (e.g.,a motor controller) may be configured to cause the one or more masstransfer devices 410, 412, 414 and 416 to move by a certain amount in aparticular direction in order to achieve the desired weight distributionfor a particular pitch and/or roll moment.

FIG. 5 illustrates a partial cross-sectional side view of thetrack-based mass transfer system 400 illustrated in FIG. 4. In thisembodiment, the track 602 is located substantially along a centralhorizontal plane or equator of the hull 102. The mass transfer device600 is shown riding inside the track 602 on the interior equator of thehull 102. In other embodiments, the mass transfer device 600 may belocated on the exterior equator of the hull 102. The mass transferdevice 600 may travel, slide or roll on the track 602 to a desiredlocation as determined by the controller.

FIG. 6 illustrates a partial perspective view of a mass transfer device600 that travels along a pathway 602 of a track-based mass transfersystem according to one embodiment of the invention. In one embodiment,the mass transfer device 600 travels inside the pathway 602 using aplurality of wheels 604. The mass transfer device 600 may also include amovement device or system, which may include a motor controller 607 anda drive motor 609, to move the mass transfer device 600 along thepathway 602. The drive motor 609 may be coupled to a drive wheel 608with gears and/or teeth that rotate such that, during operation of thedrive motor 609, the gears and/or teeth on the drive wheel 608 engage arail 610 and cause the mass transfer device 600 to move along thepathway 602 in the desired direction. The mass transfer device 600 mayalso include a telemetry terminal 612 positioned adjacent to, on top of,or as a part of the drive motor 609. The telemetry terminal 612 mayinclude an acceleration and/or position sensor for sensing or measuringinformation pertaining to the mass transfer device 600 and transmittingthe information via a wireless link to the central processing unit 1002(see also FIG. 10). The information may include the position of the masstransfer device 600 on the pathway 602, the acceleration, speed and/ordirection of the mass transfer device 600, whether the mass transferdevice 600 is functioning properly, and so on.

FIG. 7 illustrates an end view of the mass transfer device 600 of FIG. 6positioned inside the pathway 602 of a track-based mass transfer systemaccording to one embodiment of the invention. The plurality of wheels604 are coupled to the mass transfer device 600 to permit the masstransfer device 600 to move freely but securely along the pathway 602.

FIG. 8 illustrates a perspective view of the mass transfer device 600 ofFIG. 6 according to one embodiment of the invention. According to oneembodiment, the mass transfer device 600 may include eight wheels 604positioned along the perimeter or at each corner of the mass transferdevice 600 to contact the surfaces of the pathway 602. In oneembodiment, the mass transfer device 600 may include one or moreelectrically conductive contacts 614 configured to transmit controlsignals to the motor controller 607 to cause the mass transfer device600 to move in a particular direction, a certain distance or at acertain speed. Alternatively, optically conductive couplers may be usedin place of the electrically conductive contacts 614, to transmit thecontrol signals to the motor controller 607. The electrically conductivecontacts 614, or optically conductive couplers, move along and areelectrically coupled to a power slip ring 616 over which the controlsignals are transmitted to the mass transfer device 600.

FIG. 9 illustrates a side view of the mass transfer device of FIG. 6according to one embodiment of the invention. According to oneembodiment of the invention, a plurality of drive motors 609 a and 609 bmay be used to propel or move the mass transfer device 600. As shown,the drive motors 609 a and 609 b may be positioned at each end of themass transfer device 600. One or more telemetry terminals 612 can beused for each mass transfer device 600.

According to one embodiment of the invention, the power slip ring 616,which may be attached to the pathway 602, may include one or moreelectrically conductive strips for providing power to the motors 609 a,609 b on the mass transfer device 600. The mass transfer device 600 mayinclude one or more electrically conductive contacts 614 (e.g.,contacts, wheels and/or wires) that are in contact with the electricallyconductive strips so that power can be carried to the motors 609 a, 609b via the motor controller 607. Power may be provided to theelectrically conductive strips by a separate power unit, such as one ormore batteries, fuel cells, generators, solar cells, etc., or anycombination thereof. The power unit(s) may be located at any convenientpoint(s) on the airship 100.

In one embodiment of the mass transfer device 600, a power source 611(e.g., a battery, a fuel cell, a generator, etc.) is mounted directlyon, and made a part of, each mass transfer device 600. The power source611 is capable of driving or powering the motors 609 a, 609 b to movethe mass transfer device 600 along the pathway 602. In one embodiment,the power source 611 includes one or more batteries, which may berecharged via the electrically conductive strips.

By placing the power source 611 directly on the mass transfer device600, the power source 611 itself serves as part of the total overallweight of the mass transfer device 600 that is needed to effectuatepitch and/or roll stability control for the airship 100. Thisconfiguration advantageously reduces the total weight that the airship100 would otherwise need to carry if the power source 611 was placedseparately from the mass transfer device 600.

Other power sources, including hydrogen fuel cells, solar cells,generators and/or internal combustion engines, may be employed to powerthe motors 609 a, 609 b on the mass transfer device 600 via the powerslip ring 616. For instance, solar cells may be mounted on the exteriorof the hull 102 of the airship 100 to convert light energy intoelectricity that can be used by the mass transfer system.

According to one embodiment of the invention, the direction in which themotors 609 a, 609 b rotate is controlled by the motor controller 607.For example, the motor controller 607 may reverse the current to themotors 609 a, 609 b to change the direction in which the mass transferdevice 600 moves along the pathway 602. The mass transfer device 600 mayalso include a brake system to secure it to a certain position on thepathway 602 when the motors 609 a, 609 b are not activated. The brakesystem may lock the position of the mass transfer device 600 relative tothe pathway 602 so that it doesn't freely move as a result of movementby the airship 100. The brake system may be controlled or activated bythe same control system that controls the motion of the mass transferdevice 600.

The overall weight of the mass transfer system (i.e., the total of theweight of each mass transfer device 600) will vary depending upon theweight of the airship 100 in question and the desired degree of pitchand/or roll control. The overall weight of the mass transfer system maybe distributed equally or unequally amongst each mass transfer device600, as necessary to achieve the desired results.

FIG. 10 is a block diagram illustrating a control system 1000 forcontrolling the mass transfer devices of FIG. 6 to adjust the pitchand/or roll of the airship 100 according to one embodiment of theinvention. The control system 1000 includes a central processing unit(CPU) 1002 that receives input signals from a pitch and roll sensor 1004(e.g., gyroscope with one or more accelerometers), a pitostatic probe1006 and/or other data gathering devices, which can measure air speed,pitch angle, yaw angle, angle of attack, and/or outside temperature, andan accelerometer and/or position sensor located at each telemetryterminal 612. The CPU 1002 may include a telemetry terminal towirelessly transmit information to and wirelessly receive informationfrom one or more telemetry terminals 612. The accelerometer and/orposition sensor in each telemetry terminal 612 provides the CPU 1002with signals corresponding to the position on the pathway 602 of eachmass transfer device 600, the acceleration, speed and/or direction ofthe mass transfer device 600, whether the mass transfer device 600 isfunctioning properly, and so on. The CPU 1002 receives these signals andprovides a corresponding pitch signal, roll signal and/or center ofgravity signal to each motor controller 607 of the mass transfer devices600. The motor controller 607 in each mass transfer device 600 isconfigured to receive these signals and transmit these signals to thedrive motor 609 to cause the mass transfer device 600 to move accordingto the location/position indicated by the pitch signal, roll signaland/or center of gravity signal received from the CPU 1002. Thetelemetry terminal 612 may provide a feedback signal to the CPU 1002 toindicate a current position, acceleration, speed, direction and/orcondition of the mass transfer device 600. In one embodiment, a pilot oroperator may override the motor controller 607 and manually command oneor more drive motors 609 to move to a desired position.

FIGS. 11A and 11B illustrate top views of a track-based mass transfersystem having multiple mass transfer devices 1102-1112 used to adjust avehicle's center of gravity and provide pitch and roll stabilityaccording to one embodiment of the invention. In addition to providingpitch and/or roll stability, the track-based mass transfer system canalso be used to adjust the vehicle's center of gravity and/or angle ofattack, thereby enhancing its stability at speed.

Typically, airships locate their center of gravity aft of where thecenter of pressure forms on the hull. This configuration leads topronounced pitch, roll and yaw moments (sometimes referred to as“porpoising”), which generally increase in intensity as airspeedincreases. The mass transfer system 400 performs well at low airspeedsand/or while hovering, where pitch and roll moments are relatively mild,but would be placed under increasingly higher demands at higherairspeeds. To minimize the demands on the mass transfer devices 410,412, 414, 416, the mass transfer system 400 can also be configured toshift the airship's center of gravity toward the center of pressurewhile the airship 100 is operating at higher speeds, thereby decreasingthe intensity of the pitch and roll moments that the mass transfersystem 400 is called upon to counteract. This is accomplished by addingtwo or more mass transfer devices to the mass transfer system 400, asmore particularly described below.

In one embodiment, the airship 100 is a lenticular disc and thereforefunctions as a low aspect ratio wing, which generates even greaterpitching moments than a traditional cigar-shaped airship. Accordingly, alenticular airship may need larger control surfaces, which would negatemany of the aerodynamic advantages of the lenticular disc shape.Therefore, the use of the mass transfer devices to adjust the center ofgravity, while advantageous to all airship designs, may be particularlyadvantageous to a lenticular disc shaped airship such as airship 100.

In one embodiment of the invention, an airship 100 employs six (6) masstransfer devices 1102-1112 located along tracks positioned along theinternal equator of the airship 100. At any given time, two (2) of thosemass transfer devices (e.g., 1106 and 1108) may remain fixed anddedicated to maintaining the center of gravity (CG) at a given position(the “fixed CG mass transfer devices”), while the other four (4) masstransfer devices (e.g., 1102, 1104, 1110 and 1112) may move along theirrespective tracks to stabilize the airship 100 by correcting pitchand/or roll moments (the “variable stability mass transfer devices”).

As discussed above, an airship becomes unstable at and above a certainairspeed, which airspeed will vary depending upon the exact type andprofile of the airship. For illustrative purposes, the speed at which aparticular airship becomes unstable in flight is defined herein as “Xknots.” Whether a particular mass transfer device functions as a fixedCG mass transfer device or a variable stability mass transfer devicewill depend upon the airspeed of the airship (i.e., whether the airshipis traveling at an airspeed less than X knots, or at an airspeed equalto or greater than X knots).

FIG. 11A illustrates the position of the six (6) mass transfer devices1102-1112 of a mass transfer system at an airspeed less than X knots.The mass transferring devices 1106 and 1108 function as fixed CG masstransfer devices and are placed in a stationary position near the centerof the hull 102 to locate the center of gravity at the center ofbuoyancy, while the mass transfer devices 1102, 1104, 1110 and 1112function as variable stability mass transfer devices and are free tomove along their respective tracks as required to control the pitchand/or roll moments. This configuration is considered optimal formaximizing pitch and roll stability at an airspeed less than X knotsand/or while hovering.

FIG. 11B illustrates the position of the same six (6) mass transferdevices 1102-1112 at an airspeed equal to or greater than X knots. Themass transferring devices 1102 and 1104 (which function as variablestability mass transfer devices at airspeeds below X knots as depictedin FIG. 11A) are now moved forward and placed in a stationary positionat the terminus of their respective tracks to function as fixed CG masstransfer devices. The mass transfer devices 1106 and 1108 (whichfunction as fixed CG sleds at airspeeds below X knots as depicted inFIG. 11A) now function as variable stability mass transfer devices andhence are free to move along their respective tracks as needed tocontrol the pitch and/or roll moments. This configuration moves thecenter of gravity forward and is considered optimal for maximizing pitchand roll stability at airspeeds equal to or greater than X knots. Inaddition to their function as variable stability mass transfer devices,the mass transfer devices 1106, 1108, 1110 and 1112 can be positioned tovary the airship's angle of attack to maintain a constant lift (orvariable lift as desired) as airspeed changes.

FIG. 12A illustrates a movable gondola 106 attached to tracks 1202 and1204 for adjusting the airship's center of gravity by moving the gondola106 forward or aft along tracks 1202 and 1204. With respect to adjustingan airship's center of gravity, this system functions in a mannersimilar to, and accomplishes the same result as, the mass transfersystem described above. At low airspeeds and/or while hovering, thegondola 106 will be positioned at the center of the hull 102, causingthe center of gravity to be located at the center of buoyancy. Asairspeeds increase, the gondola 106 will move forward along tracks 1202,1204, causing the center of gravity to move forward as required forstability.

FIG. 12B illustrates one or more movable propulsion motors 104A and 104Bfor adjusting the airship's center of gravity by moving one or morepropulsion motors 104A and 104B forward or aft along one or more tracks1206 and 1208. With respect to adjusting an airship's center of gravity,this system functions in a similar manner to, and accomplishes the sameresult as, the mass transfer system described above. At low airspeedsand/or while hovering, the one or more propulsion motors 104A and 104Bare positioned near the midpoint of the hull 102, causing the center ofgravity to be located at the center of buoyancy. As airspeeds increase,the one or more propulsion motors 104A and 104B move forward alongtracks 1206 and 1208, causing the center of gravity to move forward asdesired. The one or more propulsion motors 104A and 104B may be mountedto the tracks 1206 and 1208 by means of a coupling mechanism that allowsthe one or more propulsion motors 104A and 104B to swivel as necessaryto maintain a forward orientation while moving along the tracks 1206 and1208.

FIG. 13 illustrates another embodiment of the mass transfer system,which includes a fluid mass transfer system 1300 in which one or morefluid conduits or lines 1302 selectively distribute a fluid to one ormore tanks 1304 positioned near the internal or external equator of anairship 100 to control the pitch and/or roll of the airship 100 asdesired, in a similar manner to the track-based mass transfer system400. One or more sensors (e.g., 1004 and 1006) are used to detect thepitch and/or roll of the vehicle and provide one or more correspondingoutput signals. An on-board controller or CPU 1002 receives the one ormore output signals from the one or more sensors and provides one ormore signals to cause the transfer of fluid to and from one or more ofthe plurality of tanks 1304 to achieve a desired vehicle pitch and/orroll orientation. The fluid mass transfer system 1300 may include one ormore pumps coupled to the plurality of lines 1302 to move the fluid toand from one or more of the plurality of tanks 1304. Additionally, aplurality of valves may be coupled to the plurality of lines 1302 tocontrol fluid flow to and from one or more of the plurality of tanks1304. The controller may selectively activate or deactivate the one ormore pumps and/or the plurality of valves to achieve a desired vehiclepitch or roll orientation.

The plurality of fluid lines 1302 radiate outwards from the centerportion of the airship 100 and are used to selectively distribute afluid to one or more reservoir tanks 1304 positioned near the internalor external perimeter of the hull 102. The mass transfer system 1300 isable to transfer fluid to the one or more tanks 1304 located inside oroutside the hull 102, but near the equator of the vehicle 100, tostabilize and/or tilt the airship 100 in any direction and along anyaxis and to control the location of its center of gravity.

FIG. 14 illustrates a block diagram of the fluid mass transfer system1300 for controlling the movement of an airship 100 according to oneembodiment of the invention. The fluid mass transfer system 1300 mayalso include a plurality of pumps 1402, 1404 that serve to pump a fluidfrom one tank to another, thereby achieving a desired weightdistribution. A plurality of conduits or pipes and valves may beemployed as part of the fluid mass transfer system 1300. For example, apipe 1302A carries fluids from the tank 1304A to the pump 1402 and thento the tank 1304B (via the pipe 1406) or to a storage reservoir 1408(via the pipe 1416). The pipes 1406 and 1410 may include one-way valves1412 and 1414, respectively, to prevent the fluid from flowing in thewrong direction. The pumps 1402 and 1404 may be coupled to the storagereservoir 1408 using the pipes 1416 and 1418, respectively, which can beused to carry the fluid to/from the storage reservoir 1408, as needed.

According to one embodiment of the invention, the fluid mass transfersystem 1300 includes a control unit 1420 (e.g., a computer-controlleddigital system or analog system) that controls the operations of thepumps 1402 and 1404 to transfer mass (e.g., fluid) between the tanks1304A and 1304B and/or the storage reservoir 1408 to achieve the desiredorientation of the airship 100. One or more sensors 1422 may provideroll or pitch information to the control unit 1420 so that it maycontrol the fluid mass transfer system 1300 accordingly. For instance,if it is desired to tilt the airship 100 in a first direction, fluid maybe pumped into the tank 1304A, from the tank 1304B and/or the storagereservoir 1408, to increase the weight at that part of the airship 100.

FIG. 15 illustrates a top view of a fluid mass transfer system 1500 forcontrolling the pitch and/or roll of an airship 100 according to anotherembodiment of the invention. In this embodiment, four tanks 1502, 1504,1506, 1508 are arranged or disposed around the interior equator of thehull 102. The four tanks 1502, 1504, 1506, 1508 are interconnected by abi-directional fluid transfer conduit 1510 that forms a ring around theinterior of the hull 102. The bi-directional fluid transfer conduit 1510serves to transfer fluid between tanks 1502, 1504, 1506 and 1508 tocause the vehicle to roll and/or pitch as desired.

The fluid mass distribution system 1500 may include a plurality ofbi-directional pumps 1512, 1514, 1516 and 1518 to pump the fluid throughthe conduit 1510 in either direction. The bi-directional pump (e.g.,1512) may be placed between two tanks (e.g., 1502 and 1504) to pump thefluid between those tanks. Additionally, check valves 1520 and 1522 maybe placed along or in-line with the conduit 1510 at one or both sides ofa tank 1506 to control the flow of fluid. That is, the check valves 1520and 1522 may be opened or closed to either retain fluid in a particulartank or permit the fluid to flow to a tank further down the conduit1510.

While various airships have been described, the mass transfer systemsdisclosed herein may be implemented in many other vehicles (e.g., hybridaircraft, blimps, boats, ships, airplanes, underwater craft, submarines,etc.) and mediums (air, water and space) where stability, pitch and/orroll control, and/or center of gravity control are desired. Forinstance, the mass-transfer system may be implemented in a watercraft(e.g., boat, ship, racing yacht) to provide pitch and roll controland/or stability. In such watercraft implementations, the mass-transfersystem may be similar to the ones described above and may be locatedinside or outside of the watercraft's hull.

While certain exemplary embodiments have been described and shown in theaccompanying drawings, it is to be understood that such embodiments aremerely illustrative of and not restrictive on the broad invention, andthat this invention not be limited to the specific constructions andarrangements shown and described, since various other changes,combinations, omissions, modifications and substitutions, in addition tothose set forth in the above paragraphs, are possible. Those skilled inthe art will appreciate that various adaptations and modifications ofthe just described preferred embodiment can be configured withoutdeparting from the scope and spirit of the invention. Therefore, it isto be understood that, within the scope of the appended claims, theinvention may be practiced other than as specifically described herein.

1.-11. (canceled)
 12. A system for providing pitch and roll stability toa vehicle, comprising: a pathway disposed adjacent to a perimeter of thevehicle; a mass transfer device movably coupled to the pathway; and acontroller configured to cause the mass transfer device to move from afirst location on the pathway to a second location on the pathway toachieve a desired pitch or roll orientation.
 13. The system of claim 12wherein the mass transfer device includes a motor configured to receivea signal from the controller to move the mass transfer device.
 14. Thesystem of claim 12 further comprising a power source attached to and forproviding power to the mass transfer device.
 15. The system of claim 12wherein the mass transfer device includes a brake to secure the masstransfer device to the pathway.
 16. The system of claim 12 furthercomprising a sensor for determining a pitch or roll movement of thevehicle and for providing a signal to the controller to move the masstransfer device. 17.-26. (canceled)
 27. An airship comprising: a hullhaving an inner surface and an outer surface, the inner surface isconfigured to contain a gas under a pressure greater than atmosphericpressure; a propulsion device coupled to the outer surface of the hull;a sensor for detecting a pitch or roll moment of the hull; a pathwaypositioned around a central perimeter of the hull; a plurality of masstransfer devices configured to move along the pathway; and a controldevice for receiving a pitch signal or a roll signal and, using thepitch signal or the roll signal, controlling the movement of theplurality of mass transfer devices along the pathway to achieve adesired pitch or a desired roll of the hull.
 28. The airship of claim 27further comprising a weight attached to each of the plurality of masstransfer devices.
 29. The airship of claim 27 further comprising a powersource attached to and for providing power to the plurality of masstransfer devices.
 30. The airship of claim 29 wherein the power sourceis selected from a group consisting of a battery, a fuel cell, a solarcell, a generator, a motor and an engine.
 31. The airship of claim 27wherein each of the plurality of mass transfer devices includes a braketo hold the mass transfer device at a particular position on thepathway.
 32. The airship of claim 27 further comprising a track coupledto the outer surface of the hull and to the propulsion device forallowing the propulsion device to move along the track to a positionthat adjusts the airship's center of gravity toward the airship's centerof pressure.
 33. The airship of claim 27 further comprising a cabincoupled to the outer surface of the hull.
 34. The airship of claim 33further comprising a track coupled to the outer surface of the hull andto the cabin for allowing the cabin to move along the track to aposition that adjusts the airship's center of gravity toward theairship's center of pressure.
 35. An airship comprising: an enclosedhull containing a gas; means for providing propulsion; means forallowing the movement of a mass within the hull; a plurality of masstransfer devices that move along the means for allowing the movement ofa mass within the hull; and means for receiving a pitch signal or a rollsignal and, using the pitch signal or the roll signal, controlling themovement of the plurality of mass transfer devices along the means forallowing the movement of a mass within the hull to achieve a desiredpitch or a desired roll of the hull.
 36. The airship of claim 35 furthercomprising a weight attached to each of the plurality of mass transferdevices.
 37. The airship of claim 35 further comprising one or morepower sources attached to and for providing power to each of theplurality of mass transfer devices.
 38. The airship of claim 35 whereinthe one or more power sources are selected from a group consisting of abattery, a fuel cell, a solar cell, a generator, a motor and an engine.39. The airship of claim 35 wherein the mass transfer device includes abrake to hold the mass transfer device at a particular position on themeans for allowing the movement of a mass within the hull.
 40. Theairship of claim 35 further comprising a track attached to the hull andto the means for providing propulsion for allowing the means forproviding propulsion to move along the track to a position that adjuststhe airship's center of gravity toward the airship's center of pressure.41. The airship of claim 35 further comprising a cabin coupled to thehull.
 42. The airship of claim 27 wherein the plurality of mass transferdevices are configured to move along the pathway to a position thatadjusts the airship's center of gravity toward the airship's center ofpressure.